Bradfield, who is one of the testimonial patrons, will be VIP guest at the Spirit of Wales Testimonial Dinner at Twickenham Stadium tomorrow evening. A huge rugby fan, the lead guitarist and singer of the Blackwood group pinpointed Williams as one of the greats of his generation.

He said: "I've followed Welsh rugby since childhood, was a regular at the old Cardiff Arms Park, and Martyn's many moments of brilliance on the pitch have long been one of the highlights of being a Welsh rugby fan.

"I know I can't have been the only one who was delighted when he returned from retirement in 2008, and played such a key role in winning that Six Nations Grand Slam."

Bradfield added that it was an honour to be backing the testimonial year.

"Martyn has proved to be one of the great sportsmen of his generation, but his determination, dedication and modesty transcends the boundaries of sport, and is inspirational to everyone who knows him," he said.

Martyn Williams, who will play for Wales in Saturday's Six Nations opener against England, said he was looking forward to launching his testimonial in style, but reminded his opponents that rugby was still top of the agenda.

He said: "I'm looking forward to a great evening, but first and foremost I'm still playing rugby, so I'll be building up to the big game on Saturday. I'd like to thank everyone who is supporting the testimonial year."